The present invention relates to orthodontics and is more particularly concerned with a new and improved orthodontic arch wire that is used as the force imparting component in orthodontic appliances.
In the field of orthodontics, a force imparting wire is used to correct irregularities and/or abnormalities in the relationship between various teeth within the dental arch. The wires are elastically deformed and absorb and release energy during loading and unloading so as to provide a force magnitude that will rapidly and relatively painlessly move the teeth with minimum tissue damage. The wire applies a constant force level over time in order to provide appropriate tooth movement with maximum tissue response. Thus, as can be appreciated, in order to provide proper and effective treatment, it is necessary to position or locate the arch wire accurately on the patient for maximum effective treatment.
Arch wires are frequently preformed and provided with a marking at the mid-point of the wire to assist in locating the wire on the patient. This marking typically consists of a spot of ink or vegetable dye that has been FDA-approved for that use. However, the dye is not permanent, is easily removed and frequently wears off or is wiped off as the arch wire is being applied to the patient. Additionally, the vegetable dye is typically light in color and difficult to identify. Thus, it is quite easy for the arch wire to be placed on the patient in an inaccurate position. This mispositioning of the wire can be further aggravated if the wire tends to slide from side to side during mounting or adjustment and, under such conditions, the posterior sections of the wire may be displaced by an extent sufficient to even injure the patient.
In accordance with the present invention, it has been found that the mid-point can be permanently, visibly, and accurately designated on the wire in such a way that it not only can be readily observed by the orthodontist but will facilitate removal and precise remounting of the wire if such is needed for necessary adjustments. This is achieved in accordance with the present invention by providing a visible, tactilely discernable arch wire mid-point indicator that is not only easily identified, but will resist or limit excessive sideways movement thereby avoiding the possibility for slidable mispositioning and the requirement for repositioning the wire. Accurate positioning in turn reduces the office time of the patient and permits the orthodontist to proceed rapidly with the appropriate adjustment of the wire on the patient. These results are achieved without adversely impacting the primary functional characteristics of the arch wire while simultaneously assuring repeatedly accurate positioning thereof.
Other features and advantages of the present invention will be in part obvious and in part pointed out more in detail hereinafter.
These and related features are achieved in accordance with the present invention by providing an orthodontic arch wire of uniform longitudinal cross-section curved in a generally U-shaped configuration. This curved arch defines both a principal plane of the wire as well as a center line for the arch within the plane. In accordance with the present invention, the arch wire is provided at its center line with a mid-point indicator in the form of a displaced wire portion such as a wire segment or dimple that is offset from the principal plane of the arch wire but does not disrupt the continuous radial curvature of the arch wire at its center line and at the wire segments immediately adjacent thereto.
The displaced wire portion at the center of the arch wire extends outwardly above the plane of the wire only a very slight distance, which distance is sufficient to cooperate with brackets mounted on the patient's central incisors so as to impede movement of the displaced portion past the mesial portion of the central incisor brackets. Since the mid-point marker is offset from the plane of the wire by only a slight degree, it performs no function with respect to the movement of the teeth and provides no adverse impact on the shape of the arch wire. However it does clearly limit the sliding movement of the wire within the arch without altering the thickness or cross-section of the wire at the mid-point.
A better understanding of the invention will be obtained from the following detailed description and the accompanying drawings of illustrated applications of the invention wherein the features, properties and relation of element are described and exemplified.